The configuration is stored in /etc/netdata/charts.d/apache.conf.
To edit this file on your system run /etc/netdata/edit-config charts.d/apache.conf.

The internal default is:

# the URL your apache server is responding with mod_status information.apache_url="http://127.0.0.1:80/server-status?auto"# use this to set custom curl options you may needapache_curl_opts=# set this to a NUMBER to overwrite the update frequency# it is in secondsapache_update_every=